<template>
  <div>
    <h1>computed</h1>
    {{ arr }} - {{ len }}
  </div>
</template>

<script lang="ts">
import Vue, { computed, reactive, ref } from 'vue'
export default {
  setup () {
    const arr = ref(['a', 'b', 'c', 'd'])
    const len = computed(() => arr.value.length)
    return {
      arr,
      len
    }
  }
}
</script>
